Computing device



A. W. VANCE COMPUTING DEVICE Dec. 1, 1953 Filed April 29, 1949 XOMN... Souwmf Patented Dec. 1, 1953 COMPUTING DEVICE Arthur W. Vance, Cranbury, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application April 29, 1949, Serial No. 90,359

6 Claims.

This invention relates to computing devices which are capable of multiplying a plurality of multiplicands by the same multiplier. The multiplying device herein disclosed is similar to that disclosed in my copending application Ser. No. 91,981, led May 7, 1949, in that it functions to produce voltages each of which is proportional to the product of a diierent multiplicand multiplied by the same multiplier. It is distinguished therefrom by the fact that it does not involve the use of a counter, requires only one relay for the conversion of the multiplier and is of relatively simple construction.

More particularly, the multiplying device of the present invention includes an integrator of the type disclosed in a copending application of Goldberg, Ser. No. 90,072, led April 28, 1949, and also described in an article by Goldberg in the June 1950 issue of the RCA Review, entitled "Stabilization of Wide-Band Direct-Current Ampliers for Zero and Gain. To the input of this integrator is supplied a current which is the resultant diierence between two currents. One of these currents represents the value of the multiplier divided by a resistance R. The other of these currents 2R or R (depending on the energization of the conversion relay) represents the plus or minus value of a standard voltage E divided by R. The integral of this difference current is applied to a nip-nop or trigger circuit which has its output connected to the input of an amplier. This amplifier delivers its output to a plurality of parallel-connected relays, one of which controls a feedback circuit of the amplifier and the others of which control circuits having outputs at which voltages proportional to the values of the diierent products are produced.

The principal object of the invention is the provision of an improved multiplying device and method of operation for deriving a plurality of products each equal to the same multiplier times a different multiplicand. Other objects are the.

provision of a multiplying device which is less complicated than those heretofore available, the provision of a multiplying device which does not involve counters or their required adjuncts, and the provision of a multiplying device wherein an extremely simple organization of elements is required for energizing a plurality of relays in response to predetermined values of a multiplier.

The invention will be better understood from the following description considered in connection with the accompanying drawing and its scope is indicated by the appended claims.

Referring to the drawings:

Figure 1 is a block diagram showing the relation between the various parts of the improved multiplying device,

Figure 2 is a wiring diagram of the integrator, and

Figure 3 is a wiring diagram of the flip-nop and the amplifier from the output of which the various relays are energized.

Figure 1 illustrates the multiplying device as including a plurality of resistors l0 to I8 each of which may have a value of the order of 50,000 ohms. A voltage representative of the value of the multiplier and having a maximum value of volts, for example, is applied from the terminals I9-20 through the resistor I0 to the input of an integrator 2|.

The input of the integrator 2l is also connected through the resistors Il and I2 to a terminal 22 which is maintained at a voltage 2E. A terminal 23 maintained at a voltage -E is arranged to be connected through a switch 24 to the common terminal 25 of the resistors ll and I 2. Under these conditions the input current to the in' tegrator is the difference between a current mal open position or is in its closed position as a result of energization of its operating coil 26.

The integral of this difference current builds up, due to the integrating action of the integrator 2 l, to a voltage such that (1) current conduction is transferred from one to the other side of a iiipflop 21, (2) the output current of a relay drive ampliiier 28 is increased and 3) the relay coil 26 is energized thereby closing the switch 24 and reversing the current supplied through the resistor l l to the input of the integrator. This condition is maintained until the integral is such as to nip the flip-nop the other way or back to its starting position.

Connected in parallel with the coil 26 are similar coils 29, 3e and 3| which function to close the normally open switches 32 to 3 4. These switches are connected in similar fashion tocircuits which are similar to the one to which switch 24 is conriected. vThe similar circuits are theresistors I3 and I4, I5 and I6, I1 arid I8, each of which has the value R. The rst of these circuits has applied (l) to its input terminal 35 a voltage +21/ which is representative of twice the value offa first multiplicand and (2) to its input terminal 3S a voltage y. The second circuit has applied to its terminals voltages +22 and Y#a whichsirni- Since'thefstandard-yoltages 2E and ,E are fixed, this means that the average conductance of vthe relayresistor system, tthrough lwhich kthis feedba'ekA takes =place, vis proportional to a1. If the conductance G of this feedback relay resistor systemis deed asits'ability to carry current or the reciprocal ofthe resistance, :then

nl RE The system. failsfof course when "a: exceeds E whereupon therelay is'closed all the time. AI a: approaches E the relay operates less vandless frequently. If "p20 the relay spends lhalffthe time infe'achposition. .'.In practice, the value-of :bis notallowed to exceed in vwhich-case rtherepetition, rate, of the rela?,

variesflessfthan twoarto `one-asm varies. 4*The i natural frequency of the system is determined by the time constant ofthe integrator and the ip voltage of the dip-flop.

Since the conductance, or ability tocarry current, of the converter relay resistor systniis the conductance, or ability to carry"irrerit,'of the resistor systems of 'similar relays in series or parallel which are simultaneously operated is also If thesecontrolled relays have thesame' resistor systems and are excited by avoltage proportional to the other variable, as shown, the producteurrents are:

rRE RE RE The output current f rornieach ofth'ese various systems is a current'proportional to the product ofthe two'variables. This may be converted in Well known 'frsllioh` to (a voltage.

etc.

To summarize, the current applied to the input of the integrator will have a positive or a negative polarity dependent upoi'i whether relay contact 24 is or is not applying E to the resistor network. The time required for the output of the integrator to build up to a given voltage level, either positive or negative, or to go from a positive output level to a negative output level when the 'integrator in'put is positive, and 'to go from a negative output level to a positive output level, is substantially determined, in a given integrating 'amplien by the amplitude of the charging current available for the condenser connected betweenfthe inpu'tfandoutput of the integrating amplier `(condenser 5I in Figure 2 of the drawings). This charging current is of course deter- .mined bythe,voltage input to the integrator.

Since the flip-flop can only be turned over when the integrating amplifier attains the given voltage level, and since, between flip-dop turnovers contact 24-'either rests in its open position 'o'rin its position of application of the voltage -'E,"-it should beapparentthat Athe length of timeltlie relay remains in'either of Vits two position'sfdel pends upon the -'iriputfto the integrator. IThe onlyvariable -ap'p'liedto the-input of the'system is the voltage It may therefore be seenthat the -length of time the relay contact vremains longer in Tone of its t'wo positions th'aninithe other isdeterr'nined by-the amplitude'o'f'vthe 'applied voltage a: (whic'h o'neof Ythe tw'o l'p'ositio'nrfis determined by-the=polarityofm `Since the ability of the relay-resistor network lvfto 'pass current is v determined by the operation of vthe relay c'o'ntact, which l in'fturn is determinedi by'the "value of the conductance G1 yof `the network mayb'e said to be proportional-tom or equal to the'product of r and a constant. This constant'is Therefore,

la; Gm

It is also interesting to'note that the relay-resistor network consisting of relay 26 and resistors I I and I 2 arein'what maybe considered arr-electro-mechanical-type of feedback network between the integrator output and itsV input. The average value of the feedbak'current through this network equals the inputcurrent or Identical resistora'relay networks 'having 1 their relays operated identically with` the operation jf relay '2e-win nave-tue same' conductance. lIf a voltage Y isV applied'to any one f the identical' resistor-relay networks in the same "manner-fas thel voltage 'E' was applied to the orfigin'alrelayf resistor network, namely 4 as -l-"ZY )and -Y, )the average output current :of the network "is the product-of the conductance'ofthe' system andthe applied voltage'or f Figure: 2 showsthe i integrator 2 I Aiasstabilized for zero and drift inthe manner disclosed cle-- tall by,-.theeaforesaid` Goldberg application. lilc-I aficiursafA tually, any type of integrating amplifier may be used which is stabilized for zero and drift, such as the integrating amplier shown in the article by Ragazzini et al. in the Proceedings of the I. R. E. for May 1947.. However, the integrating amplifier which is described in the application and article by Goldberg is preferred, since it is easily stabilized. It includes an input terminal 44 from which the potential at the common terminal of the resistors I and l l is applied (l) to the input of a first stage 45 and (2) to the xed contact 46 of a chopper or vibrator 41.

The amplier stage 45 is direct-coupled through amplifier stages 48 and 49 to an output terminal 50 which is connected to the flip-flop 21 of Figure 1. A feedback circuit including a capacitor is connected from the output terminal 50 to the input terminal 44.

'I'he chopper 41 performs two functions. First it chops or converts to A. C. any error voltage so that it may be amplified by an A. C. amplifier including amplifier stages 52 and 53. Second its xed contact 54 is utilized to synchronously rectify the output voltage of the A. C. amplifier and apply the output as a zero and drift correction voltage to the grid 55 of the input stage 45 of the integrator. Movement of the chopper contact 56 is effected by means of a coil 57 which may be energized from a 6() cycle source. Under these conditions, the integrator is stabilized for zero and drift.

Figure 3 shows the nip-flop of Figure 1 as including a pair of tubes 58 and 59 which have their grids each cross-connected to the anode of the other so that current conduction is stable in either one or the other of the tubes and is shifted from one to the other in response to the application of a positive pulse to the grid of a nonconducting tube or to the application of a negative pulse to the grid of a conducting tube.

The grid `60 of the tube 59 is connected to the output terminal 50 of the integrator and the grid 6| of the tube 58 is connected to the grids `52 and 63 of a pair of parallel-connected amplifiers 64 and 65. These amplifiers deliver their output through a resistor 66 (shunted by a capacitor 61) to the relay coils 26, 29, 30 and 3l which have been identified in connection with Figure 1.

Assuming the tube 59 of the flip-flop 21 to be conducting, the application of a more negative voltage from the integrator 2l to the grid 60 causes current conduction to be transferred from the tube 59 to the tube 58. As a result, the voltage of the anode -68 becomes more positive. This is also true of the grids 6I, 62 and 63 which are connected to the anode 68 through a 250,000 ohms resistor 69. The effect of this more positive voltage is to increase the output of the ampliers 64 and B5 to the relay operating coils 26 and 29 to 3l. This causes the relays to be operated. When conduction is transferred back to tube 59, a more negative voltage is applied to the grids B2 and 63, thus causing the amplifiers to be less conductive and the relays are released.

As explained in connection with Figure 1, the relays thereafter function in such a way that the average value of the feedback current is made exactly equal to and currents representative of the values of the various products are made available at the output leads 4l, 42 and 43.

From what has been said, it is evident that the ratio of the currents supplied by the relays in' the plus and minus positions should be the same for each of the multiplying circuits as for theV standard circuit. Obviously the illustrated type of relay may be replaced by any other type of relay adapted to perform the same function.y Thus, yany type of current controlling relay capable of having its effective conductance varied in response to an on and off signal will produce' the desired result. It is to be understood, therefore, that the term relay as herein used is intended to include such devices as a D. C. balanced modulator, a diode switch, a magnetically controlled cathode ray tube, etc.

What the invention provides is a very simple time division type of multiplying device which. requires a number of tubes, switches and other circuit components that is small as compared. to those required by similar multiplying devices heretofore available.

What is claimed is:

1. In a device for producing a voltage proportional to the product of a multiplier times a multiplicand y, the combination of a plurality of resistors; an integrator; means including the first of said resistors for supplying to the input of said integrator la current proportional to the value of r; a converter unit including (1) firstand second fixed-voltage input leads of oppositev polarity, (2) an output lead, (3) a separate pair of said resistors connected in series between said output lead and the first of said input leads and (4) a relay switch adapted to connect said second input lead to the common terminal of said series-connected resistors only when its operating coil is energized; means connecting the output lead of said converter unit to the input of said integrator; a multiplier unit having circuit components similar to those of said converter unit and having its relay coil interconnected with the relay coil of said converter unit; and means interconnecting the output of said integrator and said coils for establishing in the resistor systems of said units -a conductance proportional to said value of x.

2. A device as set forth in claim 1 wherein the means interconnecting the output of said integrator with said coils are a flip-flop circuit responsive to the output of said integrator, and an amplifier responsive to the current conducting condition of said flip-nop circuit.

3. A device as set forth in claim 1 wherein the rst and second input leads of said multiplier.-

unit are charged to Xed voltages which are of opposite polarity and are proportional to the value of y.

4. In a device for producing a voltage proportional to the product of a multiplier :c times a multiplicand y, the combination of an integrator; means for supplying to the input of said integrator a current proportional to the value of rc; a converter unit including a pair of seriesconnected resistors connected to said integrator input and a relay, means coupling said relay to said integrator output to have the energization of said relay controlled from the output of said integrator, means coupled to said relay and said series connected resistors for applying to the input of said integrator a fixed voltage which has one polarity when said relay is deenergized and has the opposite polarity when said relay is energized; a multiplier unit including a relay and a pair of resistors having circuit constants similar with those of said converter unit, means coupling said multiplier relay to said integrator output to have; the energizaniorrA of.;` saint' relayf controlled fromnthe: Output: ofsrzsaid( integratorA forl `esta-b1 ish--` ing: in;A said multiplier Aunit` resistors aI conducta ance proporbionalto the value oi mi' andmeans for.Y applying to. the; resistorsofcsaid multiplying' unita voltage which is proportional to the, vali- 1a ofsy and whicnhasrits polarity dctermnediby the openA `or closedcondition of the, relav-Y of l:said mule tipiier. unit..

5,- A; device. as. setz forth in claim imherein therev i's;,connected between theyoutpntof' said integrator andi the 'g energizing elementsA of saidt relaysiailip-op lcircuit responsive tof the 'output of said integrator; and:arr,ampliersresponsive tothecurrent conductive condition offfsaici-flipnon circuit;

6.: a Y device for -multiplying za; phiurality:y of

multiplicands by .the same mnltip1ier, timeA combination gof an integrator; means for vsupplying to the input of said integratore. cturent'i.loro," portional to the value of saidrgmu-ltiplier; aqconverter` unitincluding' (i). a resistance network haringen Outputalead connectedto the input of sadiintegrator and (.2)` a relay, means-coupling said-relay to: said .integratonoutput to control thefenergization ofs said relay with the outputofy said integrator, means` coupled to. said resistance.

networlr` and said-relay for producing at said output ieadja xedvoltage which has or-ielpoliirity` when. saidrelax is. deenergized and has the oppositapolarity when said reIayisener-gizedr; a

plurality-'otzmultiplierlunits each having a relay4 andina/resistor network havingfcircuit constants identicaltthose of said converter units,- each of which vis;:proportional4 to, .the value, of a different oneof-ksaid;multiplicands; and has its` polarity. determined by the opened or closed' condition :of the relaypf said' uni-t.

, ARTHUR W. VANCE.;

No. references cited, 

